This program controls a strip of ten lights by two pairs of photocells at bottom and top stairs. A count signal prevents the lights from getting dark when someone is walking along the stair.
The pro ...

Mounths ago I built an [url=http://elettronicaetecnologia.blogspot.com/2011/07/earthquake-alarm-circuit-schematic.html]earthquake detector that works by an high sensitive pendulum. Not a seismograph ...

This was my first circuit using digital counters. Two cd4017 drive a led strip from L1 to L8 and from L8 to L1. The counters work alternately due to the clock enable signal.
The circuit in the video ...

I don't know what exactly you are doing, but if you want the low period longer than the high period you can invert the signal from the output of the 555.
(instead of the pin 15) it should work.
Take ...

Here you can find a simple project based on 4017IC
http://elettronicaetecnologia.blogspot.com/2011/05/led-driver-circuit.html
You can make it faster by using smaller capacitors.
If you are new to e ...